The present invention relates to an information recording and reproducing apparatus, and more particularly to a moving position detecting apparatus of a mobile element used in a disk apparatus of the like.
In a conventional disk apparatus of magnetic disk or optical disk, a pickup device is moved to an innermost circumferential position or outermost circumferential position of a disk. A position detecting apparatus detects when the pickup apparatus is moved to a specified position. Thus, the specified operation of the pickup apparatus is done automatically.
As the position detecting means, hitherto, a push type switch has been used. In this case, when the pickup apparatus is moved to an innermost circumferential position or outermost circumferential position of a disk, the pickup apparatus pushes this push type switch from its moving direction, thereby detecting that the pickup apparatus has reached the innermost circumferential position or outermost circumferential position.
In the push type switch, when a pressing work force larger than specified is applied to the pressing knob portion, the pressing knob portion is moved by overcoming the elastic force (reaction force) of the spring in the switch. When the pressing knob portion moves more than a specific distance, an electric contact is opened or closed. When the pressing force of the pressing knob portion is eliminated, it is restored to the initial state by the thrusting force of the spring. Therefore, when the pressing work force and the reaction force are not mutually balanced, that is, when the reaction force by the push type switch and the pressing work force by the pickup apparatus are not adjusted properly, if the pickup apparatus is sent to the innermost circumferential position or outermost circumferential position of the disk along the radial direction of the disk, the push type switch cannot be driven. Moreover, if the pickup apparatus is driven, the pickup apparatus may be shifted from the specified position by the reaction force of the switch after driving.
A position detecting apparatus of the invention for detecting the moving position of a mobile element comprises:
A mobile element moving reversibly along a specified running path,
a conductive electrode disposed along the running path,
a detecting electrode disposed on the mobile element, and
detecting means for detecting contact or non-contact between the conductive electrode and detecting electrode.
In which, the detecting electrode is disposed so as to contact with or not to contact with the conductive electrode by the move of the mobile element. The position of the mobile element is detected by the detecting means.
Preferably, the position detecting apparatus further includes a guide shaft for guiding the move of the mobile element, and the conductive electrode is disposed on the surface of the guide shaft.
Preferably, the position detecting apparatus further includes a guide shaft for guiding the move of the mobile element, and the conductive electrode is disposed on the surface of the guide shaft, and the detecting electrode is disposed so as to may contact electrically with the conductive electrode from the direction crossing with the moving direction of the detecting electrode.
Preferably, the position detecting apparatus further includes a guide shaft for guiding the move of the mobile element, and a drive shaft for moving the mobile element, and the conductive electrode is disposed on the surface of the drive shaft.
Preferably, the position detecting apparatus further includes a guide shaft for guiding the move of the mobile element, a drive shaft for moving the mobile element, and an elastic member disposed between the drive shaft and the mobile element, and the conductive electrode is disposed on the surface of the drive shaft.
In this constitution, application of reaction to the mobile element is prevented. Moreover, move of the mobile element from the specified position is lessened and eliminated.